On Fri, Feb 21, 2020 at 06:20:08PM +0100, Jiri Pirko wrote:

Fri, Feb 21, 2020 at 05:51:41PM CET, madhuparnabhowmik10@gmail.com wrote:

quoted

From: Madhuparna Bhowmik <redacted>

list_for_each_entry_rcu() has built-in RCU and lock checking.

Pass cond argument to list_for_each_entry_rcu() to silence
false lockdep warning when CONFIG_PROVE_RCU_LIST is enabled
by default.

Signed-off-by: Madhuparna Bhowmik <redacted>

Reviewed-by: Jiri Pirko <redacted>

Thanks.

However, there is a callpath where not devlink lock neither rcu read is
taken:
devlink_dpipe_table_register()->devlink_dpipe_table_find()
I guess that was not the trace you were seeing, right?

quoted

---
net/core/devlink.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/core/devlink.c b/net/core/devlink.c
index 4c63c9a4c09e..3e8c94155d93 100644
--- a/net/core/devlink.c
+++ b/net/core/devlink.c

@@ -2107,7 +2107,8 @@ devlink_dpipe_table_find(struct list_head *dpipe_tables,

{
	struct devlink_dpipe_table *table;

-	list_for_each_entry_rcu(table, dpipe_tables, list) {
+	list_for_each_entry_rcu(table, dpipe_tables, list,
+				lockdep_is_held(&devlink->lock)) {

Hi Jiri,

I just noticed that this patch does not compile because devlink is
not passed as an argument to devlink_dpipe_table_find() and it is not
even global. I am not sure why I didn't encounter this error before
sending the patch. Anyway, I am sorry about this.
But it seems to be the right lock that should be held and checked for
in devlink_dpipe_table_find(). 
So will it be okay to pass devlink to devlink_dpipe_table_find()?
Anyway devlink_dpipe_table_find() is only called from functions
within devlink.c.

Let me know what you think about this.
Thank you,
Madhuparna

quoted

		if (!strcmp(table->name, table_name))
			return table;
	}
-- 
2.17.1